352 THE BIOLOGY OP^ THE FROG chap. 



bodies against the stone floor, or by creeping under the 



rocks usually kept there. It therefore seems that the 



frog is stereotropic [thigmotactic] in temperatures between 

 io° C. and 4° C." 



REFERENCES 



Graber, V. Grundlinien zur Erforschung des Helligkeits- und Far- 

 bensinnes der Thiere. Prag and Leipzig, 1884. 



Loeb, J. Comparative Physiology of the Brain, and Comparative 

 Psychology. New York, 1900. 



Parker, G. H. The Skin and Eyes as Receptive Organs in the Reac- 

 tions of the Frog to Light. Am. Jour. Phys., Vol. 10, 1903. 



Torelle, E. The Response of the Frog to Light. Am. Jour. Phys., 

 Vol. 9, 1903. 



Yerkes, R. M. The Instincts, Habits, and Reactions of the Frog. 

 Monogr. Suppl. Psychol. Rev., Vol. 4, 1903. 



